Pipe junction restrainers and techniques for their assembly have been developed to make fluid-tight connections between two axially-aligned pipes, joints, valves, fittings, hydrants, or other types of fluid connections. Often, these junction restrainers must withstand extraordinarily great pressures associated with water distribution and sewer connections. Such devices may include, for example, segmented or split pipe joint retainer glands, which are well known and typically are secured together around a pipe section by ears or lugs formed on, or extending radially outwardly from, the gland segments.
It has been current practice to employ polyvinyl chloride (PVC) plastic pipe in new construction. One popular system employed for connecting PVC pipe, sold under the trademark CERTA-LOK.TM. and produced by CertainTeed Corporation, Valley Forge, Pa., provides a rather unique restrained joint between a pair of pipe sections for municipal, fire protection and other uses. The joint connector uses a series of o-ring seals and internal annular cavities that are filled externally with polymeric dowels after two sections of PVC pipe are inserted into the connector. These dowels also fill matching annular cavities located on the pipe sections to form a restraining mechanical lock that has a rating of 150 psi and up. Since the restraining mechanism of the CERTA-LOK.TM. joint connector is uniformly distributed around the PVC pipes, the risk of damaging the plastic sidewalls by localized stress fracture can be minimized.
It has been recently understood that the CERTA-LOK.TM. system permits each of the axially-aligned plastic pipes to rotate relative to one another after they are joined together. Such pipes often connect to a fluid pump, which creates torque throughout the piping system and may cause rotation of one or both pipes during the pumping of fluids. An excessive amount of rotation may cause damage due to abrasive wear on the outside of the pipe, or breakage to the electrical wires, and/or supporting cable for the pump.
One method of preventing the relative rotation of pipes coupled using a CERTA-LOK.TM. pipe connection system has been to install set screws through the tubular fitting member surrounding the pipe. Although this method has some effect on reducing rotation, the effect is often of limited value. Additionally, the lateral forces created by overtightening the set screws tend to push the pipes out of alignment, which has been known to cause some fluid leakage.